KR20030033412A - Apparatus and method for optical power monitoring in optical transmission system - Google Patents

Abstract

PURPOSE: A device and a method for monitoring optical power of an optical transmission system are provided to eliminate an external change factor in an optical power monitoring structure for transmission signals of a WDM(Wavelength Division Multiplexing) device, so as to correctly measure the optical power. CONSTITUTION: An amplification unit(100) amplifies optical signals received from a remote station, and extracts optical signals in modules processing the optical signals to perform internal optical power monitoring. An optical power monitoring unit(200) performs optical power monitoring in the external of the amplification unit(100), to measure entire optical power of the optical signals and optical power/wavelength values according to each channel. And a monitoring control unit(300) corrects the measured optical power value externally monitored in the optical power monitoring unit(200), with reference to a measured optical power value internally monitored in the amplification unit(100), while providing a monitoring control function in a system.

Description

Apparatus and method for optical power monitoring in optical transmission system

The present invention relates to optical power monitoring of an optical transmission system, and more particularly, to optical transmission for eliminating external factors in an optical power monitoring structure for a transmission signal of a wavelength division multiplexing (WDM) device to enable an improvement in operating quality of a system. An optical power monitoring apparatus of a system and a method thereof are provided.

Generally, Dense Wavelength Division Multiplexing (DWDM) or Wavelength Division Multiplexing (WDM) is a technique of loading various types of data from different places on a single optical fiber, and each signal is transmitted on a separate optical wavelength. WDM allows multiplexing on up to 80 separate wavelengths or data channels on a single fiber. If each channel is 2.5Gbps, a maximum speed of 200 billion bits per second can be transmitted in one optical fiber.

In WDM, each channel is demultiplexed with the original signal at the receiver, so that multiple data formats with different rates can be transmitted together. That is, Internet data, SONET data, and ATM data can all be simultaneously transmitted in the optical fiber.

1 is a block diagram of an optical power monitoring apparatus of a general WDM system.

According to Figure 1, the general configuration for measuring the optical power from each module performance unit of the WDM system is amplifying unit 100 for amplifying the received signal, the total optical power and the optical power / wavelength value for each channel by measuring The optical power monitoring unit 200 for reporting, and the operating software is downloaded and operated while the monitoring control unit 300 to perform the monitoring control function in the system is made.

The main input signal of the WDM is the main optical link signal 400 received from the power station, and the main output signal is the main optical link signal 401 transmitted in the direction of the power. The main input signal is connected to the main output signal through a supervisory drop filter 101, an optical amplifier 103, and a supervisory add filter 102, and is extracted and inserted. The control monitoring signal is connected to the outside through the connection port 106.

Light 104 and 105 from each module is connected to an external optical power monitoring unit 200 using patch cords 501 and 502. Then, the optical power monitoring unit 200 detects the power of the optical signal received through the patch cords 501 and 502 and transmits the measured optical power value to the monitoring control unit 300 through a separate signal line 600. do.

At this time, the inside of the optical power monitoring unit 200 usually detects light in a PIN photodetector, and converts a current value that varies according to the amount of photons absorbed (photon energy) into an electric circuit in a voltage. After digitizing, it is digitized and displayed again.

For example, in case of 20G-WDM optical power monitoring function module, it uses optical splitter to separate the optical signal for monitoring purpose from the original signal so that it can be connected to the outside, and receives the optical input from the outside to perform the power monitoring function. There are separate units, which are connected to each other externally via a jumper cord.

However, in the conventional optical power monitoring method, the optical power measurement of each channel and optical amplifier of WDM is inaccurate during the initial installation and maintenance of the system (in the case of the actual case, the difference may be about 1 to 2 dB). It is difficult to set and the error range is relatively wide, which can be a problem.

As described above, the accuracy of the jumper cord connected to the external port and the port status of each unit are not only different, but there is no optical power measurement unit for the entire WDM transmission signal. have.

The present invention was created to solve the above-mentioned conventional problems, and an object of the present invention is to provide stable operation through accurate optical power measurement by eliminating external change factors in the optical power monitoring structure for the transmission signal of the WDM device. It is to provide an optical power monitoring device of the optical transmission system that enables it.

The optical power monitoring apparatus of the optical transmission system of the present invention for achieving the above object, amplifies the optical signal received from the power station, and extracts the optical signal from the modules processing the optical signal to perform internal optical power monitoring A unit; An optical power monitoring unit for performing optical power monitoring outside the amplification unit to measure the total optical power of the optical signal and the optical power / wavelength value of each channel; And a supervisory control unit for calibrating the externally monitored optical power measurement value in the optical power monitoring unit with reference to the optically monitored optical power measurement value in the amplification unit while performing the supervisory control function in the system. .

Another object of the present invention is to compare the internal and external optical power measurement values in the optical power monitoring structure for the transmission signal of the WDM device by calibrating the external optical power monitoring to improve the operation quality of the optical system of the optical transmission system It is to provide a power monitoring method.

The optical power monitoring apparatus of the optical transmission system of the present invention for achieving the above object is measured by performing optical power monitoring at the same time as the optical power monitoring in the unit including the module to be measured of the WDM equipment, respectively Comparing the optical power values; If the measured optical power values are different from each other, correcting the externally monitored optical power values according to the internally measured optical power values; And performing optical power monitoring on the optical signals to be measured by using the external optical power monitoring when the calibration is made or when the optical power values respectively measured in the inside and the outside are the same. do.

1 is a block diagram of an optical power monitoring device of a typical WDM system.

2 is a block diagram of an optical power monitoring apparatus of an optical transmission system according to an embodiment of the present invention.

Figure 3 is a detailed view of the power monitoring unit in the unit in Figure 2;

4 is a flowchart illustrating an optical power monitoring method of an optical transmission system according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: amplification unit 101: control monitoring signal extraction unit

102: control monitoring signal insertion unit 103: amplification unit

104, 105: Monitoring tab 106: External connection port

200: optical power monitoring unit 300: supervisory control unit

400: Main input signal 401: Main output signal

501, 502: patch cord 600, 801, 802: measurement value transmission signal line

700: unit optical power monitoring unit 800: control signal line

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

2 is a block diagram of an optical power monitoring apparatus of an optical transmission system according to an embodiment of the present invention, Figure 3 is a detailed view of the power monitoring unit in the unit in Figure 2, Figure 4 is a view of the optical transmission system according to an embodiment of the present invention The optical power monitoring method is a flowchart.

The present embodiment maintains an external connection in a WDM device as in the prior art, but has a circuit for measuring optical power by itself through a photodetector inside the unit to be measured, and transmits the optical power value measured in this way. Has a set of configurations.

According to Figure 2, the present embodiment to measure the optical power from each module performance unit of the WDM system, amplifies the optical signal received from the power station, and extracts the optical signal from the modules processing the optical signal to the internal An amplifying unit 100 for performing optical power monitoring; An optical power monitoring unit (200) for performing optical power monitoring outside of the amplification unit (100) to measure the total optical power of the optical signal and the optical power / wavelength value for each channel; The supervisory control unit 300 for calibrating the externally monitored optical power measurement value by the optical power monitoring unit 200 with reference to the optical power measurement value internally monitored by the amplification unit 100 while performing the in-system monitoring control function. It is made, including.

In the case of the main optical link signal 400 corresponding to the main input signal of the WDM and the main optical link signal 401 corresponding to the main output signal, the main input signal includes the control monitoring signal extracting unit 101 and the optical signal. The amplifier 103 and the control monitoring signal insertion unit 102 are connected to the main output signal, and the control monitoring signal extracted and inserted is connected to the outside through the connection port 106.

In addition, according to Figure 4, the monitoring target optical signal is divided into two. The part where the monitoring optical signal from the amplification unit 100, the module under measurement, goes to the port for external connection (the signal of 104 or 105 is connected to 501 or 502), and the connection part 104 or 105 for internal measurement. To 700). At this time, since the optical signal from each module is extracted before and after the amplifier 103, one signal is branched through the optical power monitoring tap (104) before amplification, and the other signal is optical power after amplification. It branches through the monitoring tab 105. Each tap typically branches about 1% of the total signal.

Optical power monitoring on the outgoing portion of the two branched optical signals is performed in the same manner as in the prior art. That is, the optical signal from each module is connected to the external optical power monitoring unit 200 using the patch cords 501 and 502. Then, the optical power monitoring unit 200 detects the power of the optical signal received through the patch cords 501 and 502 and transmits the measured optical power value to the monitoring control unit 300 through a separate signal line 600. (S41).

The internal connection portion detects the optical power of the optical signal from each module by using the power monitoring unit 700 in the unit, and amplifies the optical power using the external optical power monitoring unit 200 described above. The optical power is measured internally in the unit 100 (S42).

In this case, the function of distributing the optical signal from each module to the external optical power monitoring unit 200 and the internal optical power monitoring unit 700 may be easily implemented using a splitter or the like. Preferably, the splitter distributes the optical signals 104 and 105 evenly to the inside and the outside.

The power monitoring unit 700 in the unit is implemented according to the optical power measurement technology using the light detection element.

According to FIG. 3, a technology for measuring optical power by using an internal photodetecting device in a power monitoring unit 700 in a unit includes a photodetector (implemented as a photodetector) based on the amount of photons coming from the outside (710). ) And convert it into a corresponding amount of electrical form (e.g. current), and change it into the appropriate voltage form using a log amplifier 720 and an OP amplifier 730, etc. Thereafter, the digital number is stored as a digitized number through an ADC module (750), and the controller 740 reads the stored digital number to detect the optical power.

By comparing the optical power value thus read with the value measured by the external optical power monitoring unit 200, the monitoring control unit 300 can determine whether the connection of the patch cords (501, 502) is correct, these values are mutually In other cases, the supervisory control unit 300 performs a calibration thereof to optimize the optical power monitoring unit 200. The control signal transmission path 800 between the supervisory control unit 300 and the optical power monitoring unit 200 is secured to transmit the calibration control signal, and the total detected by the power monitoring units 700 in the two units, respectively. Paths 801 and 802 for ensuring that the input optical power value and the total output optical power value are transmitted to the monitoring control unit 300 are secured (S43 to S44).

Then, detailed data collection for each channel is possible through the optimized external optical power monitoring unit 200. After the calibration of the optical power measurement value of the entire signal is made, it is possible to find out the optical power for each channel more accurately, and the optical power monitoring unit 200 may perform data collection for wavelength or gain control (S45). ).

On the other hand, in a situation where the hardware configuration changes, such as when the unit is removed or the optical core is removed, the process returns to steps S41 and S42 to monitor the optical power inside and outside, and if there is no change in the hardware configuration, Returning to step S45 to continuously measure the optical power for each channel using the external monitoring unit 200 (S46).

As described above, unlike the prior art in which only one of the internal optical power measurement and the external optical power measurement is used as necessary, the present embodiment obtains an accurate optical power value by comparing two of them simultaneously.

In the prior art, there was no measurement unit for the entire WDM transmission signal, and even when such a measurement unit was provided, it was difficult to accurately eliminate optical factors that could cause measurement errors. 502) may vary depending on the connection state, so there is no unstable surface.

When the loss value of the external patch cords 501 and 502 caused by this reason is increased, even if the normal operation is actually performed, if it is judged to be an abnormal state and incorrectly controlled, the overall stability of the system may be adversely affected. In addition, the life of the device can be shortened due to accelerated aging of major optical components.

On the contrary, in the present embodiment, the optical power monitoring unit 700 measures the optical power of each main optical link signal together with the external connection, and monitors the measured value of the monitoring control unit 300. Make it accessible from. Accordingly, the monitoring control unit 300 may determine whether the patch cords 501 and 502 are connected correctly by comparing with the externally read values, and when the values are incorrect, the internal control may be performed. Internal adjustment of the supervisory control unit can be implemented using a hardware control circuit or software control logic.

Accurate optical power measurement for the main optical link enables accurate measurement of individual channel measurements, greatly contributing to overall system reliability. In practice, the function of the optical power monitoring unit 200 is to collect data for measuring and correcting the optical power or wavelength variation of each channel, rather than the overall optical power, depending on the accuracy of the overall power measurement as described above. This can be determined.

In addition, if the automatic gain control is made during the service as one of the possible embodiments, it is possible to adjust the total optical power or optical power for each channel, thereby providing elasticity in system operation.

The embodiments described above are within the scope of various changes, modifications, and equivalents of the present invention. Therefore, the present invention is not limited to the description of the examples.

According to the optical power monitoring apparatus and method of the optical transmission system of the present invention, accurate optical power can be measured for the main optical link, so that accurate collection of data for measurement and correction of optical power or wavelength variation for each channel is achieved. System performance is improved.

Claims (4)

An amplifying unit for amplifying an optical signal received from a power station and extracting the optical signal from the modules processing the optical signal to perform internal optical power monitoring; An optical power monitoring unit for performing optical power monitoring outside the amplification unit to measure the total optical power of the optical signal and the optical power / wavelength value of each channel; And a supervisory control unit for calibrating the externally monitored optical power measurement value in the optical power monitoring unit with reference to the optically monitored optical power measurement value in the amplification unit while performing the supervisory control function in the system. Optical power monitoring device. The method of claim 1, wherein the amplification unit, An amplifier for amplifying the optical signal input from the power station; A plurality of monitoring tabs for branching the optical signal before amplification at the front end of the amplifying unit, branching the optical signal after amplification at the rear end of the amplifying unit, and transferring each branched optical signal to the optical power monitoring unit; An optical power monitoring unit in the unit for monitoring each optical signal branched from each monitoring tap to measure optical power before amplification and optical power after amplification, and for transmitting each measured optical power value to the monitoring control unit; Optical power monitoring device of the optical transmission system, characterized in that made by. The method of claim 2, The optical power monitoring unit in the unit is characterized by branching the half of the optical signal branched from each monitoring tap so that the optical signal of the same power is transferred between itself and the optical power monitoring unit so that the optical power is measured. Optical power monitoring device of the optical transmission system. Performing optical power monitoring inside the unit including the module under measurement of the WDM equipment and performing optical power monitoring outside thereof to compare the measured optical power values; If the measured optical power values are different from each other, correcting the externally monitored optical power values according to the internally measured optical power values; And performing optical power monitoring on the optical signals to be measured using the external optical power monitoring when the calibration is made or when the optical power values respectively measured inside and outside are the same. Optical power monitoring method of optical transmission system.